National Blood Centre director Soisaang Pikulsod said the supplies of Rh-negative blood groups had been very low for the past few months. As a reult, the centre was unable to meet requests for 177 units from more than 200 hospitals nationwide.

The current demand is for 71 units of O Rh-negative, 66 units of A Rh-negative and 40 units of B Rh-negative.

“Only one Thai in every 1,000 has this special blood type, so it’s a rare blood group,” said Dr Soisang. “The average daily demand is five to ten units but only between three and five units are donated daily.

“I appeal to those having Rh-negative blood to help donate in order to help our fellow human beings.”

Dr Soisaang said the severe shortage represented a serious threat to patients in need of the special blood groups. They include many people in comas and some awaiting major heart or brain surgery, and child delivery.

The number of patients born with rare blood types has increased dramatically in recent years, she noted, and each one would need between three and five units of blood during an operation.

People having Rh-nagative and other rare blood types are urged to donate at the National Blood Centre.